I recently purchased Expert F# and I'm quite satisfied with it. It goes well beyond syntax and into best practices. It also includes some excellent glue work for various targets such as web development and managed Direct X. The level of detail it goes through means a slow read and it skips over trying to teach you the basics of programming. I read it in a few days verses an afternoon which is normal for me and a technical book.

I'm interested to see if the section on decoding compiler error messages will be useful at some point. The book covers Functional, Imperative, Object Oriented, and Language Oriented programming in F#. The section on OOP was a bit short however the book mentions that this section was kept short on purpose to help you get away from pure OOP. The few mastering chapters are really good at taking F#'s syntax and clarifying how it works.

I highly recommend this book based on it being information rich and fluff free.